<template>

  <div class="app-container">

    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="active" finish-status="success" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="发布课程"/>
    </el-steps>

    <!-- 课程信息表单-->
    <el-form ref="courseInfo" :model="courseInfo" :rules="rules" label-width="120px">

      <el-form-item label="课程标题" prop="title">
        <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
      </el-form-item>

      <!-- 所属分类：级联下拉列表 -->
      <el-form-item label="课程类别" prop="subjectId">
        <!-- 一级分类 @change="subjectLevelOneChanged" -->
        <el-select
          v-model="courseInfo.subjectParentId"
          placeholder="请选择"
          @change="subjectLevelOneChanged">
          <el-option
            v-for="subject in subjectNestedList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"/>
        </el-select>
        <!-- 二级分类 -->
        <el-select v-model="courseInfo.subjectId" placeholder="请选择">
          <el-option
            v-for="subject in subSubjectList"
            :key="subject.value"
            :label="subject.title"
            :value="subject.id"/>
        </el-select>
      </el-form-item>

      <!-- 课程讲师 -->
      <el-form-item label="课程讲师" prop="teacherId">
        <el-select
          v-model="courseInfo.teacherId"
          placeholder="请选择">
          <el-option
            v-for="teacher in teacherList"
            :key="teacher.id"
            :label="teacher.name"
            :value="teacher.id"/>
        </el-select>
      </el-form-item>

      <el-form-item label="总课时" prop="lessonNum">
        <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/>
      </el-form-item>

      <!-- 课程简介-->
      <el-form-item label="课程简介" prop="description">
        <tinymce :height="300" v-model="courseInfo.description" placeholder=" 示例：简介"/>
      </el-form-item>

      <!-- 课程封面-->
      <el-form-item label="课程封面">
        <el-upload
          :show-file-list="false"
          :on-success="handleAvatarSuccess"
          :before-upload="beforeAvatarUpload"
          :action="BASE_API+'/admin/oss/file/upload?host=cover'"
          class="avatar-uploader">
          <img :src="courseInfo.cover">
        </el-upload>
      </el-form-item>

      <!-- 课程价格 -->
      <el-form-item label="课程价格" prop="price">
        <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
      </el-form-item>
    </el-form>

    <div style="text-align:center">
      <el-button :disabled="saveBtnDisabled" type="primary" @click="next()">保存并下一步</el-button>
    </div>
  </div>
</template>

<script>
import course from '@/api/edu/course'
import teacher from '@/api/edu/teacher'
import subject from '@/api/edu/subject'
import Tinymce from '@/components/Tinymce'

const defaultForm = {
  title: '',
  subjectId: '',
  subjectParentId: '',
  teacherId: '',
  lessonNum: 0,
  description: '',
  cover: process.env.OSS_PATH + '/cover/banner-1-blue.jpg',
  price: 0
}

export default {
  components: { Tinymce },
  data() {
    // 添加学生账号的正则
    const validNumber = (rule, value, callback) => {
      if (value <= 0) {
        callback(new Error('请填写大于0的数字'))
      } else {
        callback()
      }
    }
    return {
      BASE_API: process.env.BASE_API, // 接口API地址
      active: 0,
      courseInfo: defaultForm,
      saveBtnDisabled: false, // 保存按钮是否禁用
      teacherList: [], // 讲师列表
      subjectNestedList: [], // 一级分类列表
      subSubjectList: [], // 二级分类列表
      rules: {
        title: [
          { required: true, message: '请输入课程标题', trigger: 'blur' }
        ],
        subjectId: [
          { required: true, message: '请选择课程类别', trigger: 'change' }
        ],
        teacherId: [
          { required: true, message: '请选择讲师', trigger: 'change' }
        ],
        lessonNum: [
          { required: true, message: '请填写总课时', trigger: 'blur' },
          { validator: validNumber, trigger: 'blur' }
        ],
        description: [
          { required: true, message: '请填写课程简介', trigger: 'blur' }
        ],
        price: [
          { required: true, message: '请填写课程价格', trigger: 'blur' }
        ]
      }
    }
  },

  watch: {
    $route(to, from) {
      this.init()
    }
    // 'courseInfo.subjectParentId'(newVal, oldVal) {
    //   this.subjectNestedList.filter(e => {
    //     if (e.id === newVal) {
    //       this.subSubjectList = e.children
    //       this.courseInfo.subjectId = ''
    //     }
    //   })
    // }
  },
  created() {
    this.init()
  },

  methods: {

    init() {
      // 获取讲师列表
      this.initTeacherList()

      // 路由有id就是修改,没有就是新增
      if (this.$route.params && this.$route.params.id) {
        const id = this.$route.params.id
        // 根据id获取课程基本信息回显
        this.fetchCourseInfoById(id)
      } else {
        // 没有id值,清空表单对象
        this.courseInfo = { ...defaultForm }
        // 初始化分类列表
        this.initSubjectList()
      }
    },

    next() {
      this.saveBtnDisabled = true
      if (!this.courseInfo.id) {
        this.saveData()
      } else {
        this.updateData()
      }
    },

    // 保存
    saveData() {
      this.$refs.courseInfo.validate(valid => {
        if (valid) {
          course.saveCourseInfo(this.courseInfo).then(response => {
            this.$message({
              type: 'success',
              message: '保存成功!'
            })
            return response// 将响应结果传递给下一个then
          }).then(response => {
            this.$router.push({ path: '/edu/course/chapter/' + response.data.courseId })
          })
        } else {
          return false
        }
      })
    },

    fetchCourseInfoById(id) {
      course.getCourseInfoById(id).then(response => {
        this.courseInfo = response.data.item

        subject.getNestedTreeList().then(response => {
          this.subjectNestedList = response.data.items
          // 填充二级菜单
          this.subjectNestedList.filter(e => {
            if (e.id === this.courseInfo.subjectParentId) {
              this.subSubjectList = e.children
            }
          })
        })
      })
    },

    updateData() {
      this.saveBtnDisabled = true
      course.updateCourseInfoById(this.courseInfo).then(response => {
        this.$message({
          type: 'success',
          message: '修改成功!'
        })
      }).then(() => {
        // 跳转到下一步
        this.$router.push({ path: '/edu/course/chapter/' + this.courseInfo.id })
      }).catch((response) => { // 失败
        this.$message({
          type: 'error',
          message: '修改失败'
        })
      })
    },

    initTeacherList() {
      teacher.getList().then(response => {
        this.teacherList = response.data.items
      })
    },

    initSubjectList() {
      subject.getNestedTreeList().then(response => {
        this.subjectNestedList = response.data.items
      })
    },

    // 二级联动
    subjectLevelOneChanged(value) {
      this.subjectNestedList.filter(e => {
        if (e.id === value) {
          this.subSubjectList = e.children
          this.courseInfo.subjectId = ''
        }
      })
    },

    // 上传封面成功的回调
    handleAvatarSuccess(res, file) {
      console.log(res)// 上传响应
      console.log(URL.createObjectURL(file.raw))// base64编码
      this.courseInfo.cover = res.data.url
    },

    // 上传文件之前的钩子，参数为上传的文件，若返回 false 或者返回 Promise 且被 reject，则停止上传
    beforeAvatarUpload(file) {
      const isJPG = file.type === 'image/jpeg'
      const isLt2M = file.size / 1024 / 1024 < 2

      if (!isJPG) {
        this.$message.error('上传图片只能是 JPG 格式!')
      }
      if (!isLt2M) {
        this.$message.error('上传图片大小不能超过 2MB!')
      }
      return isJPG && isLt2M
    }
  }
}
</script>
<style scoped>
  .tinymce-container {
    position: relative;
    line-height: normal;
  }
</style>
